Therefore, these disciplines have lower citation thresholds in the Essential Science Indicators, with the lowest citation thresholds observed in social sciences 154 , computer science 149 , and multidisciplinary sciences 147. It could be stored in liquid helium to prevent it from recombining into molecular hydrogen. Deuterium and its compounds are used as a non-radioactive label in chemical experiments and in solvents for 1 H-. Maxwell observed that the of H 2 unaccountably departs from that of a gas below room temperature and begins to increasingly resemble that of a monatomic gas at cryogenic temperatures. Electrolysis of water The is a simple method of producing hydrogen.
Archived from on 26 October 2007. Tax, title, and license not included. Harzing's Publish or Perish program calculates the h-index based on entries. However, hydrogen is the third most abundant element on the Earth's surface, mostly in the form of such as and water. Archived from on 14 March 2008. Archived from on 24 February 2008.
Hydrogen gas leaking into external air may spontaneously ignite. Each database is likely to produce a different h for the same scholar, because of different coverage. One of the first quantum effects to be explicitly noticed but not understood at the time was a Maxwell observation involving hydrogen, half a century before full arrived. Some such organisms, including the alga and , have evolved a second step in the in which protons and electrons are reduced to form H 2 gas by specialized hydrogenases in the. For hydrides other than group 1 and 2 metals, the term is quite misleading, considering the low electronegativity of hydrogen.
Scopus has better coverage of conferences, but poor coverage of publications prior to 1996; Google Scholar has the best coverage of conferences and most journals though not all , but like Scopus has limited coverage of pre-1990 publications. Hydrides Main article: Compounds of hydrogen are often called , a term that is used fairly loosely. These are the four visible lines of the Because of its simple atomic structure, consisting only of a proton and an electron, the , together with the spectrum of light produced from it or absorbed by it, has been central to the development of the theory of structure. Antoine-Laurent de Lavoisier Lavoisier produced hydrogen for his experiments on mass conservation by reacting a flux of steam with metallic through an incandescent iron tube heated in a fire. For example, if we have a researcher with 5 publications A, B, C, D, and E with 10, 8, 5, 4, and 3 citations, respectively, the h index is equal to 4 because the 4th publication has 4 citations and the 5th has only 3. Accessed on line 3 October 2007. It is radioactive, decaying into through with a of 12.
However, this finding was contradicted by another study by Hirsch. Archived from on 19 July 2011. It is used as a in methods such as. These Tax Advisors have completed advanced training covering the various investment options and how the income, gains, and losses from these investments impact current and future year tax situations. Bulletin of the Atomic Scientists. Efforts have also been undertaken with genetically modified. The process also produces , but the expensive gallium, which prevents the formation of an oxide skin on the pellets, can be re-used.
Regular passenger service resumed in the 1920s and the discovery of reserves in the United States promised increased safety, but the U. The lower heat value must also be used for fuel cells, as steam is the output rather than input. H 2 is used as the rotor coolant in at , because it has the highest of any gas. As the only neutral atom for which the can be solved analytically, study of the energetics and bonding of the hydrogen atom has played a key role in the development of. The glass prevents the small amount of radiation from getting out. Hydrogen is a concern in as it can many metals, complicating the design of pipelines and storage tanks. The key consumers of H 2 in the petrochemical plant include , , and.
Heavy water is used as a and coolant for nuclear reactors. Annual Review of Physical Chemistry. Hydrogen can react spontaneously and violently at room temperature with and to form the corresponding hydrogen halides, and , which are also potentially dangerous. H 2 has several other important uses. . New York: Oxford University Press. A molecular form called H + 3 is found in the interstellar medium, where it is generated by ionization of molecular hydrogen from.
Most hydrogen is in the form of atomic hydrogen because the atoms can seldom collide and combine. This function is particularly common in , especially in hydrides and complexes, as well as in clustered. The per unit volume of both and gas at any practicable pressure is significantly less than that of traditional fuel sources, although the energy density per unit fuel mass is higher. Elemental hydrogen from solar, biological, or electrical sources requires more energy to make than is obtained by burning it, so in these cases hydrogen functions as an energy carrier, like a battery. Archived from on 20 November 2008. External links has the text of the article.
The study of their properties is known as and their study in the context of living is known as. Hydrogen plays a particularly important role in because most acid-base reactions involve the exchange of protons between soluble molecules. Safety and precautions Hydrogen poses a number of hazards to human safety, from potential and fires when mixed with air to being an in its pure, -free form. Electrons per shell 1 Physical properties at 13. Many physical and chemical properties of hydrogen depend on the ratio it often takes days or weeks at a given temperature to reach the equilibrium ratio, for which the data is usually given. Hirsch has demonstrated that h has high predictive value for whether a scientist has won honors like membership or the.
Hydrogen also forms compounds with less electronegative elements, such as and , where it takes on a partial negative charge. The exclusion of conference proceedings papers is a particular problem for scholars in , where conference proceedings are considered an important part of the literature. Because of the discretization of postulated in early by Bohr, the electron in the Bohr model can only occupy certain allowed distances from the proton, and therefore only certain allowed energies. Deuterium compounds have applications in chemistry and biology in studies of reaction. Thus, the true predictability of future h-index is much lower compared to what has been claimed before. Procès-Verbaux du Comité International des Poids et Mesures. Hydrogen was for the first time by in 1898 by using and his invention, the.